The invention relates to an apparatus for demounting a tire secured to a wheel rim having an actuating lever supported on the wheel about a first pivot axis and a tire bead holder pivotably supported on the actuating lever about a second axis. The tire bead holder engages the bead of the tire.
A demounting apparatus of this type for pneumatic vehicle tires, which have their beads on wheel rims having radially inwardly oriented encompassing wheel flanges (see the journal "Gummibereifung" [Rubber Tires], Jananuary 1984, pp. 62-65), and in which the sidewalls of the tires wrap from the outside around the wheel flanges, is known from German Published, Unexamined Patent Application No. 35 24 664. In the known tire demounting tools, as the actuating lever pivots in the direction intended for the demounting operation, the tire bead holder engaging the tire bead pivots in the opposite direction on the actuating lever, engaging a portion of the tire bead to be released. The portion engaged by the tire bead holder is initially moved radially inward out of range of the wheel flange and then in the axial direction away from the wheel. In the known tire demounting tools, the tire bead holder shifts from a radially inwardly oriented motion into a motion oriented axially away from the wheel whenever the force exerted on the portion of the bead to be removed by the tire bead holder is approximately equal to the biasing force, provided by a spring, between the actuating lever and the tire bead holder.